Plug catcher and indicator



AP 1, 1952 T. M. RAGAN PLUG. CATCHER AND INDICATOR 2 SHEETS-SHEET 2 Filed July 25, 1946 INVENTOR. Wwmlfqaw BY QTTEIVEY 14M r w 7,4/

*l f /J/ /d 7 w gm@ a w/ j. f n k/ /7 7 /7 H/ g /HV nr/H M H i, i, .r E L if l 4 wl? Patented Apr. l, 10952 PLUG CATCHER AND INDICATOR Thomas M. Ragan, Downey, Calif., assignor to Baker Oil Tools, Ine., Vernon, Calif., a corporation of California Application July 25, 1946, Serial No. 686,087

11 Claims.

This invention relates to well tools, and more particularly to subsurface apparatus especially useful in the sealing of wells with cement slurry, liquid synthetic resins and other cementitious materials.

In the tubing method of cement wells, it is desirable to know when the charge of cementitious material has reached, or has been ejected from, the tubing string, in order that the proper amount of displacement fluid may be pumped into the tubing on top of the sealing material to insure its discharge in the required amount into the well bore. Measurement of the displacement uid alone does not give assurance that the proper amount of sealing material has been ejected from the tubing string, in view of the lack of knowledge of the exact cubic contents of the tubing string running to the top of the well bore. Reliance solely upon such measurements frequently results in the pumping of insufficient sealing material from the tubing, or results in forcing of all of the sealing material and some of the undesired displacement fluid into the well bore.

Accordingly, it is an object of the present invention to provide an improved apparatus for giving a positive indication of the location of the cementitious material in the tubing string or well bore.

A further object of the invention is to provide an improved plug catcher adapted to form part of ra tubing string, capable ci providing a positive indication that the plug has reached the location of the catcher in the tubing string, and of permitting circulation in both directions around the tubing plug without fear of inadvertently shutting off or restricting such circulation.

A further object of the invention is to provide a catcher for a tubing plug of relatively simple construction, and which prevents the plug from preventing flow of uid in either an upward or downward direction through the catcher and tubing string.

Still a further object of the invention is to provide a catcher for a tubing plug of simple and economical construction, which may be readily assembled and dismantled for cleaning and maintenance purposes.

This invention has other objects which will become apparent from a, consideration of the embodiments shown in the drawings accompanying and forming part of the present specification. These forms will now be described in detail to illustrate the general principles of the invention, but it is to be understood that such detailed description is not to be taken in a limited sense.

since the scope of the invention is best defined by the claims appended hereto.

Referring to the drawings:

Figure 1 is a longitudinal section through one form of apparatus embodying the invention disposed in a well casing;

Figure 2 is a view similar to Figure 1 with parts in a second operative position;

Figure 3 is a view similar to Figure 1 with parts in still another operative position; V

Figure 4 is a longitudinal section through a modied form of invention disposed in a well casing;

Figure 5 is a view similar to Figure 4 with parts in another position of operation; and

Figure 6 is a cross-section taken along the line 6 6 in Figure 2. The plug catcher includes an upper sub I0 adapted for threaded connection to a joint of tubing II forming part of a tubular string running to the top of the well bore. A depending cylindrical sleeve I2 is threadedly secured on the sub I0 to provide an enlarged chamber for a tubing plug I3 pumped down the tubing string in leakproof engagement with its interior wall or surface. A lower sub I 4 is threaded in the lower end of the cylinder or chamber, forming the lower portion of the plug catcher.

The upper sub I0 has a depending tubular guide extension I5 extending into the chamber I2, provided with a plurality of outwardly opening circulation ports or passages I6. The lower end I1 of the guide is tapered downwardly and inwardly, while the lower sub I4 has a plurality of spaced upwardly extending supporting lingers I8 having upwardly and inwardly inclined tapered portions I9. The distance between the lower end I'I of the guide tube I5 and the upper ends I9 of the supporting lingers is substantially greater than the length of the tubing plug I3 to be pumped down the tubing string and into the plug catcher chamber I2.

The guide tube I5 contains a plug seat 20 held in position above the circulation passages I6 by one or more frangible pins or shear screws 2|. This seat has an upwardly and inwardly inclined .tapered seating surface 22.

Although various suitable designs of tubing plugs may be used in conjunction with the plug catcher, the one illustrated in the drawings is an elongate plug of rubber or rubber-like material capable of being pumped or squeezed through restrictions or passages of substantially less diameter than the normally unrestrained diameter of the plug. This plug has peripheral lipseals 23 facing in both an upward and downward direction for efficient slidable sealing contact with the tubing wall while being pumped downward through the tubing string. The normal unrestrained diameter of the plug I3 is substantially equal to the inside diameter of the tubing string II, and may be of a slightly greater diameter to insure the effective sealing action of its lips 23 against the tubing wall.

In the form of invention disclosed in Figures l, 2, 3 and 6, the guide tube I5 has an inside diameter substantially less than the outside diameter of the tubing plug I3, whereasl the inside diameter of the plug catcher chamber I2 is substantially greater than the outside diameter of the tubing plug I3. Y

The lower end of the plug catcher is shown, for purposes of illustrating one representative use of the device, as being threaded into a tubular supporting member 24 of a packer, to which is secured a downwardly facing cup-shaped packing or swab cup 25 sealing against the wall of a casing 26 having perforations 21 through which cementitious material is to be pumped. It is to be understood, however, that the plug catcher may be used alone, or in conjunction with apparatus other than the packer specifically illustrated.

Let it be assumedthat. a charge of cement slurry is to be pumped down the tubing string I I for passage through the casing perforations 21 to form a cementitious seal around the exteriorof the casing 26. The tubing plug I3 is placed in the tubing string at the lower end of the charge of cement slurry, and the cement slurry with the plug preceding it is pumped down through the tubing string by displacement fluid on top of the slurry. A top cementing plug 28 may or may not be placed on top of the charge of cement slurry to separate it from the displacement fluid, as desired.

The plug or plugs I3, 28 and cement slurry are pumped down the tubing string I I until the plug I3 reaches the upper sub I0 of the plug catcher. Since the guide tube I5 depending from the upper sub has a much smaller diameter than the plug I3, the pressure on the fluid in the tubing string II must be increased to squeeze the plug into the guide tube. This rise in pressure affords an indication at the top of the well bore that the slurry has reached the plug catcher. The plug I3 comes to rest on the upper end 22 of the seat, with the downwardly diverging tapered surfaces 29 on the end of the plug engaging the corresponding tapered upper surface on the seat 20, to insure against squeezing of the plug through the central passage in the seat. Such engagement of the plug I3 with the seat 20 requires that the pressure on the fluids in the tubing be increased quite substantially before the shear screws 2| are disrupted. to enable such fluids to blow the plug I3 and seat 20 downwardly out of the guide tube I5 and into the enlarged plug catcher chamber I2.

The rise in pressure required to shear the screws 2I also advises the operator that the lower end of the cement slurry has reached the plug catcher. and the drop in pressure following shearing of the screws and pumping of the plug and seat into the enlarged chamber I2 indicates to the operator Vthat the cement slurry is being pumped through the plug catcher, flowing through the chamber I2 around the plug I3, and between the fingers I8 (on which the seat 20 and plug I3 have come to rest) into the central Mm,... u.. Hannah ma hmmm sub I4. through 4 the packer body 24, for discharge from the latter device, from where it passes outwardly of the casing 26 through its perforations 21. The packer cup 25 engages the casing wall above its perforations to force the cement slurry to pursue a path through the perforations 21.

The required amount of cement slurry may be pumped out of the apparatus, as by measurement determination, or, if a top cementing plug 28 is employed, the operator is advised when the top lcementing plug reaches the` plug catcher by the rise in pressure accompanying its attempt to squeeze into the restricted plug passage I5a through the upper sub ID and its depending guide tube I5. Following the placement of the required quantity of cement slurry behind the casing, any

excess slurry that may remain in the tubing string I I, plug catcher IG, I2, I4, or lower packer device 24, 25 may be pumped from the tubing string by reverse circulation; that is, by pumping downwardly through the annulus around the tubing string Il, the circulating fluid flowing down past the exterior of the packing cup 25 and up through the packer into the lower sub I4, from where it passes through the circulation passage between the supporting fingers I8 into the chamber I2, flowing around the tubing plug I3 and into the guide tube passage Ia, either through its lower end or circulating ports IB. The excess cement slurry and circulating or washing fluid proceeds up through the restricted plug passage I5a in the upper sub I0 and continues through the tubing string II to the top of the well bore.

Inthe event that there is any tendency for the reversely circulating washing fluid to elevate the tubing plug I3 towards the guide tube I5, the reverse fluid flow cannot be arrested by closing of the restricted guide tube passage I5a by the tubing plug, since the tapered surface 3U on the upper end of the latter merely engage the correspondingly tapered surface I1 at the lower end of the guide tube, the circulating fluid passing upwardly around the plug I3 and into the guide tube through the circulating ports or passages I6. Pumping of the plug into the central tube passage I5a is prevented, because its normal unrestrained diameter is substantially greater than the inside diameter of the central plug passage I5a, the upward and outward inclination of the tapered surfaces 30, I1 on the plug and guide tube tending to flare the plug outwardly, rather than pressing it inwardly into a position allowing its upward squeezing into the restricted plug passage.

In order to hold the tubing plug I3 in a generallycentral position within the chamber I2, to insure uniform flow of fluid around the plug, both while pumping cement slurry or other fluids down through the tubing string or during thereverse circulating of fluids, spaced longitudinally extending guide and centering ribs 3l may be secured to the interior of the chamber, as by welding material 32, the inner surfaces of the guide ribs 3| being positioned greater in radial extent from the axis of the chamber I2 than the-radius of the tubing plug I3. These guiding or centering ribs prevent material inclination of the plug in the chamber and insure its remaining in a vertical position substantially coaxial of the chamber, so that fluid may flow readily around the plug I3 and between the ribs 3 I.

' Inthe form of invention just described, pro.- vision is made for obtaining two different presindication obtained only as a. result of squeezingtheplug into and through the restricted passage Ia.

The plug I3 is prevented from being pumped downthrough the ,chamber I2 lto a position closing-the lower sub central passage Ilia byengagement of its lower downwardly diverging surface 29 with'the corresponding inclined seating surfaces I9 at the upper ends of the supporting 1ingers I8. Since the passage Ilia through the lower sub I4 is substantially less in diameter than the normalunrestrained diameter of the tubing plug I3', the latter cannot be pumped into the passage, its lower downwardly divergent surface 29 engaging the inclined surfaces I9 on the lingers, which tend to stretch the plug outwardly, and thus preclude its movement into the lower sub passage I 4a. In this manner, assurance is had that the plug is prevented from closing the outlet end of the plug catcher.

In the form of invention disclosed in Figures 4 and 5, the passage 33 through the upper sub Ill is substantially the `same in diameter as the inside diameter of the tubular string I I to which it is attached. Reliance is not had upon a restricted passage to give a rise in pressure indicationiupon entry of the plug I3 into the upper sub.: Instead, sole reliance is placed on the plug seat 20 initially secured to the guide tube by the shear screw 2l. Also, in this form of invention, the centering ribs 9| are omitted. In all respects, however, the plug catcher arrangement functions in substantially the same manner as the specific plug catcher disclosed in the other form of the invention, and has substantially the same advantages.

The plug catcher may be readily dismantled and reassembled, simply by unscrewing the upper and lower subs III, I4 from the cylinder I2, which permits removal of the plug I9, allows all parts tobe readily cleaned, and facilitates replacement of the plug seat 29 and shear screws ZI in the depending guide tube I5. Reassembly takes place by again threading the upper and lower subs I0, I4 into the plug catcher cylinder or chamber I2.

It is, accordingly, apparent that a plug catcher has been devised which provides a positive indication at the top of the well bore that the plug has reached the location of the catcher in the tubing string. The vplug catcher arrangement entraps the tubing plug and insures against its prevention of downward or upward flow of fluid through the apparatus. The device is economical to manufacture and maintain.

Although specific reference has been made to the entrapment of a bottom tubing plug I3 in Vthe plug catcher, it is to be understood that it could also be used to entrap a top tubing plug 28. The charge of cement slurry may be pumped down the tubing string without a bottom tubing plug, but with a top tubing plug separating the cement slurry from the following displacement fluid. The operator at the top of the well bore is advised of the fact that all of the cement slurry has been pumped into or through the plug catcher by squeezing of the top plug 28 into the restricted passage a in the upper sub I0, or by its engagement with the plug seat 29. The increase in pressure in the fiuid above this plug 28 then shears the screws 2I or squeezes it through the restricted passage into the enlarged chamber I2, permitting reverse circulation to take place to clear any excess cement slurry from the apparatus within the well casing. If desired, pumping may stop upon engagement of the top tubingcplug with the plug seat 29 and reverse circulation employed to pump the top tubing plug 28 in a reverse direction back through the tubing I I to the top of the well bore, followed by the excess cement slurry and washing uid.

While I have described several forms of my invention, what I claim and desire to secure by Letters Patent is:

l. A device of the character described connectable to a tubular string through which a flexibleplug may bepumped, including a tubular chamber larger than said plug to permit bypassing of fluid therearound when said plug is positioned in said chamber, a tube projecting into the upper end of said chamber and having means at its lower end engageable with the upper end of said plug to prevent upward pumping of said plug from said chamber, and means in the lower end of said chamber and engageable with said plug to prevent downward passage of said plug from said chamber.

2. A device of the character described connectable to a tubular string through which a ilexible plug may be pumped, including a tubular chamber larger than said plug to permit bypassing of fluid therearound when said plug is positioned in said chamber, a tube projecting into the upper end of said chamber and having means at its lower end engageable with said plug to prevent upward pumping of said plug from said chamber, a seat releasably secured to said tube to arrest downward movement of said plug through said tube, and means extending into the lower end of said chamber and engageable with said seat, when said seat is released from said tube, to prevent downward passage of said plug from said chamber.

3. A device of the character described connectable to av tubular string through which a flexible plug may be pumped, including a tubular chamber larger than said plug to permit bypassing of fluid therearound when said plug is positioned in said chamber, a tube projecting into the upper end of said chamber and having a central passage smaller in diameter than the outside diameter of said plug, the lower end of said tube being engageable with said plug when said plug is positioned in said chamber to prevent upward movement of said plug from said chamber, said tube having a passage through its sidewall permitting ow of fluid between said chamber and the central passage of said tube when said plug is in engagement with the lower end of said tube.

'4. A device of the character described connectable toa tubular string through which a flexible plug may be pumped, including a tubularchamber larger than said plug to permitl by-passing of fluid therearound when said plug is positioned in said chamber, a tube projecting into the upper end of said chamber and having a central passage smaller in diameter than the outside diameter of said plug, the lower end of said tube being engageable with said plug when said plug is positioned in said chamber to prevent upward movement of said plug from said chamber, said tube having a passage through its wall permit- 7 ting flow of iluid between said chamber and the central passage of said tube when said plug is in engagement with the lower end of said tube, and means in the lower end of said chamber engageable with said plug to prevent downward movement of said plug from said chamber.

5. A device of the character described connectable to a tubular string through which a ilexible plug may be pumped, including a tubular chamber larger than said plug to permit bypassing of uid therearound when said plug is positioned in said chamber, a tube projecting into the upper end of said chamber having 'a central passage smaller in diameter than the voutside diameter of said plug, the lower` end of said` tube being engageable with said plug' when said plug is positioned in said chamber to prevent, upward movement of said plug from said cham-ber,

vsaid tube having a passage through its wall permitting flow of iiuid between said chamber and the central passage of said tube when said plug is in engagement with the lower end of said tube, a seat releasably secured to said tube above said wall passage to arrest downward movement of said plug through said tube, and means in the lower end of said chamber engageable with said seat to prevent downward movement of said plug from said chamber.

6. A device of the character described connectable to a tubular string through which a ilexible plug may be pumped, including a tubular chamber larger than said plug to permitV bypassing of fluid therearound when said plug is positioned in said chamber, a tube projecting into the upper end of said chamber having a central passage smaller in diameter than the outside diameter of said plug, the lower end of said tube being engageable with said plug when said plug is positioned in said chamber to prevent upward movement of said plug from said chamber, said tube having a passage through its wall permitting flow of fluid between said chamber and the central passage of said tube when said plug' is in engagement with the lower end of said tube, a seat releasably secured to said tube above said wall passage to arrest downward movement of said plug through said tube, means in the lower end of said chamber engageable with said seat to prevent downward movement of said plug from said chamber, and spaced longitudinally extending ribs in said chamber for substantially centering said plug therein.

7. A device of the character described, including an upper sub ccnnectable to aytubular string through which a flexible plug may be pumped, a tubular chamber detachably secured to said upper sub, a lower sub detachably secured to said chamber, a tube depending from said upper sub and having a passage through its wall, means extending upwardly from said lower sub and having a passage through its wall, said chamber being larger in diameter than said plug and the distance between said tube and upwardly extending means being greater than the length of said plug.

8i A device of the character described. including an upper sub connectable to a tubular string through which a ilexible plug may be pumped,va tubular chamber detachably secured to said upper sub, a lower sub detachably secured to said chamber, a tube depending from said upper sub and having a central passage smaller in diameter than the outside diameter of said plug and also having a passage through its wall, means extending upwardly from said lower sub and having a passage through its wall, said chamber being larger in diameter than said plug and the distance between said tube and upwardly extending means being greater than the length of said plug.

9. A device of the character described, including an upper sub connectable to a tubular string through which a flexible plug may be pumped, a tubular chamber detachably secured to said upper sub, a lower sub detachably secured to said chamber. a tube depending from said upper sub and having a central passage smaller in diameter than the outside diameter of said plug and also having a passage through its wall, the end of said tube tapering downwardly and inwardly, means extending upwardly from said lower sub and having a passage through its wall, the upper end of said means tapering upwardly and inwardly, said chamber being larger in diameter than said plug and the distance between said tube andupwardly extendingmeans being greater than the length of said plug.

10. A device of the character described connectable to a tubular string through which a ilexible plug may be pumped, including a tube adapted to be attached to said tubular string for receiving said plug, a tubular chamber larger than said plug secured to said tube, said tube projecting into said chamber in spaced relation to the inner wall of said chamber, said tube having a passage through its wall opening into said chamber, and a seat secured in said tube above said passage.

ll. A device of the character" described connectable to a tubular string through which a Ilexible plug may be pumped, including a tube adapted to be attached to said tubular string for receiving said plug, a tubular chamber larger than said plug secured to. said tube, said tube projecting into said chamber in spaced relation to the inner wall of said chamber, said tube having a passage through its wall opening into said chamber, a seat secured in' said tube above said passage, and frangible means securing said seat to said tube.

THOMAS M. RAG'AN.

REFERENCES CITED UNITED STATES PATENTS Name Date Wickersham Feb. 9, 1943 Number 

